Spray guns of various types for years have utilized a relatively conventional construction wherein the fluid nozzle is threadedly attached to the gun body, and has located on top thereof an air cap which is retained by a threaded retaining ring to the gun body. The air cap frictionally engages a portion of the face of the nozzle. Thus, when the operator of the spray gun wishes to reorient the pattern from horizontal to vertical or vice-versa, typically he loosens the retaining ring and rotates the air cap to the desired position and thereafter tightens the retaining ring. The problem with such constructions has typically been that, when the operator rotates the air cap to the new desired position, such rotation frictionally engages the nozzle and loosens the nozzle relative to the gun body. This can result in pressurized fluid from the fluid passage leaking around the normally tight seal between the nozzle and gun body and thence into the air passages of the gun where it can eventually cause clogging or other damage to parts of the gun, such as the electronics present in a number of electrostatic spray guns.
While the use of pins is known to prevent rotation of nozzle parts, as shown by U.S. Pat. No. 1,962,911, the prior art has not advanced any solution towards this problem of the relative turning of threaded pieces within one another and, yet, which may be easily disassembled for cleaning and the like or for a change of nozzles.
It is therefore an object of this invention to provide some sort of manner for preventing rotation of the nozzle relative to the gun body and yet which may be easily released for cleaning or part exchange. It is a further object of this invention to provide such a locking mechanism which may be easily adapted to pre-existing spray guns without extensive tooling or the like, and which may be inexpensively manufactured.
It is yet a further object of this invention to provide such a locking mechanism that will remain locked, unless and until the spray cap and retaining ring are removed.